Relative abundance, Length-weight relationship, Condition factor and Sex ratio of Cichlid species (Pisces- Cichlidae) from Weija Reservoir in Ghana

2016

English

Cichlids from Weija Reservoir were assessed for relative abundance, length-weight relationship, condition factor and sex ratio to provide better knowledge of the Cichlidae family to enhance their sustainable management for reservoir fishery development, food security and sustainable development. Two out of four genera identified namely Tilapia and Hemichromis together dominated the Cichlid family accounting for over 90% and over 80% of total number and weight respectively. The two most abundant species out of seven species identified namely Hemichromis fasciatus and Tilapia guineensis constituted almost half of total number and over one-third of total weight respectively. Females were in better condition and therefore better adapted to the Weija environment than males for four species namely Hemichromis bimaculatus, Hemichromis fasciatus, Tilapia guineensis and Tilapia zillii. Similarly, for Oreochromis niloticus and Sarotherodon melanotheron males were in better condition and, therefore, better suited to the environment than females. With the exception of male Hemichromis fasciatus and male Oreochromis niloticus which showed isometric growth and female Sarotherodon melanotheron which showed positive allometeric growth, the remaining species showed negative allometric growth for both sexes. Monthly differences in sex ratio were variable for all species at 95% confidence interval except for Oreochromis niloticus. Significant differences in sex ratio were observed for each species except for O. niloticus which was not significant at 95% confidence interval. With few exceptions, all species showed strong correlation between length and weight while males generally had stronger correlations than females. Though S. melanotheron and O. niloticus had good size characteristics, they were found in limited abundance and therefore may require management intervention to increase their relative abundance.

Quarcoopome, T.